1. Field of the Invention
Aspects of the present invention relate to a proton conductive polymer electrolyte and a fuel cell including the same, and more particularly, to a solid polymer-type fuel cell stably performing for a long period of time even at an operational temperature from 100° C. to 200° C. in non-humidified conditions or a relative humidity of 50% or less.
2. Description of the Related Art
In general, fluorinated polyethylene sulfonic acid membranes are used in common salt electrolysis, a desalinization process of sea water, and water treatment, and in addition, are used as an electrolyte for a fuel cell due to its high proton conductivity and high chemical stability. Examples of commercially available fluorinated polyethylene sulfonic acid membranes include NAFION membranes, FLEMION membranes, ACIPLEX membranes, and DOW membranes.
However, these electrolytes are not environmentally friendly since they include fluorine, and are also expensive.
There are electrolytes which do not include fluorine. Examples of such electrolytes include a polystyrene sulfonic acid used as an ion exchange resin or ion exchange membrane for use in a water treatment, and a sulfonic acid aromatic polymer for use in a fuel cell (refer to Japanese Patent Publication No. hei11-502245, T. Kobayashi, M. Rikukawa, K. Sanui, N. Ogata, Solid State Ionics, 106 vol., 1998, p. 219).
However, such electrolytes are not suitable for use in fuel cells due to their heat resistance and chemical instability.
Non-aqueous proton conductive electrolytes also exist. Such non-aqueous proton conductive electrolytes can be prepared by combining a non-volatile and room temperature-molten salt, a phosphoric acid, or a low molecular weight molecule, such as imidazole, with a heat-resistant polymer. In this state, the non-volatile and room temperature-melting salt, phosphoric acid, and low molecular weight molecule, such as imidazole, act as a proton acceptor or a carrier. Most non-aqueous proton conductive electrolytes, however, are soluble with respect to water and thus can leak out of a fuel cell due to water that is generated when the fuel cell operates.